Histological Differentiation of Primordial Germ Cells in Zebrafish

Abstract

ABSTRACT-In this study, primordial germ cells (PGCs) in zebrafish were described histologically using eosinophilic granules as a marker. PGC-like cells (PL-cells) with eosinophilic granules were identified initially at the sphere stage (4-hr postfertilization), and were observed until the bud stage, the earliest stage to which PGCs with proper morphology could be traced. The morphology and distribution of eosinophilic granules in PL-cells changed during epiboly. Mitoses of PL-cells were observed only from the shield to bud stage, after eosinophilic granules aggregated to the perinuclear region in PGCs. These shifts of eosinophilic granules corresponded histologically to those of germ plasm described in Xenopus. These results suggest that eosinophilic granules represent germ plasm in fish and that PL-cells with these granules correspond to the PGCs or presumptive PGCs (pPGCs).

Germ Cell Lineage from a Single Blastomere at 8-Cell Stage in Shiro-uo (ice goby)

“…Because yolk granules were distributed in all cells of embryonic body until early segmentation period, like in goldfish (Kazama-Wakabayashi et al ., 1999), it was difficult to distinguish PGCs from surrounding somatic cells. In both zebrafish and goldfish, histological detection of PGCs is later in development than those of identification of vasa transcripts, germ line maker (Nagai et al ., 2001;Otani et al ., 2002). Therefore, it must be difficult to identify PGCs by histological characters in teleost at early developmental stage.…”

“…Serial sections were cut at a thickness of 8 µ m, and stained with hematoxylin-eosin, using standard procedures. PGCs were confirmed based on location and characteristics similar to those observed in other teleosts; round shape, relatively large size, large nuclei, and clear nuclear membrane (Hamaguchi, 1982;Timmermans and Taverne, 1989;Braat et al , 1999;Kazama-Wakabayashi et al ., 1999;Nagai et al ., 2001).…”

Developmental biotechnology for aquaculture, with special reference to surrogate production in teleost fishes

“…If the migration is mediated by different molecular mechanisms, PGCs could not move to the genital ridge in the host embryo. On the other hand, it was reported in zebrafish that the distribution of cytoplasmic components in PGCs varies during the migration period (Braat et al, 1999;Knout et al, 2000;Nagai et al, 2001). This suggests the possibility that the biochemical properties responsible for migration may change during development.…”

Isolation of teleost primordial germ cells using flow cytometry

“…Zebrafish embryos were obtained by natural spawning. Dechorionation and incubation procedures were carried out as described by Nagai et al (1999). In goldfish, we carried out artificial fertilization, developmental staging of embryos, dechorionation and incubation of embryos as described by Kajishima et al (1960), Yamaha et al (1986Yamaha et al ( , 1998Yamaha et al ( and 1999 and Otani et al (2002), respectively.…”